Tube drawing machine



Jan. 10, 1961 J. w. LAWRENCE 2,957,500

TUBE DRAWING MACHINE Filed May 22, 1953 5 Sheets-Sheet 1 Jan. 10, 1961J. w. LAWRENCE TUBE DRAWING MACHINE 5 Sheets-Sheet 2 Filed May 22. 1953Jan. 10, 1961 J. w. LAWRENCE TUBE DRAWING MACHINE 5 Sheets-Sheet 3 FiledMay 22, 1953 Em F/GZ! Jan. 10, 1961 J. w. LAWRENCE TUBE DRAWING MACHINE5 Sheets-Sheet 4 Filed May 22. 1953 Jan. 10, 1961 J. w. LAWRENCE TUBEDRAWING MACHINE 5 Sheets-Sheet 5 Filed May 22. 1953 7 F/GQ.

' ea xac United States Patent Ofiice v Patented Jan. 10, 1961 TUBEDRAWING MACHINE John William Lawrence, Leicester, England, assiguor toLawrence Holdings (Overseas) Limited, London, England Filed May 22,1953, Sen N0. 356,866

5 Claims. (Cl. 113-34) This invention relates to tube drawing machines,and has reference particularly to such machines for producing lockseamed tubes for use in the construction of core structures of thefinned tube type.

Finned tube core structures are embodied in heat exchange apparatussuch, for instance, as radiators for use in conjunction with liquidcooled internal combustion engines, and are alternately known as coresof the gilled tube or fin and tube type.

A finned tube core structure comprises a plurality of tubes, usually ofa flat or oval section, these tubes extending through spaced finsadapted to provide heat dissipating or radiating surfaces.

Conventional methods of producing these tubes require the provision of alarge machine including a plurality of pairs of shaped rollers adaptedprogressively to form the tube in a number of successive stages. Theoutput of such known machines, as well as their capital cost, is veryhigh, and as a consequence their use is confined to large undertakings.

The object of the present invention is to provide a machine of simpleconstruction and low capital cost designed to produce efiicient tubes ata rate more suited to the needs of the smaller manufacturer.

The machine constituting this invention essentially includes a die headcomprising appropriately contoured fixed die parts or portions betweenwhich an initially flat strip of relatively thin and easily deformablemetal can be drawn, the said fixed parts or portions being adapted toconvert this metal from the flat condition into lock seamed tubing.

Thus, the die head embodies opposed and laterally spaced complementarydie parts or portions which are fixed, in contra-distinction to beingrotatable as are rollers, but which, like the pairs of rollers in theprior costly machines, are adapted for action upon strip metal suchwiseas to form tubing therefrom in progressive stages.

In one convenient embodiment of the invention, the die head incorporatesa continuous and unitary fixed die which may advantageously be made byany appropriate one of the modern precision casting methods.Alternatively, what is in effect a continuous fixed die may be built upin sections, or it may even be produced by electro deposition on wax orequivalent patterns or forms.

Moreover, instead or" providing in the simplified machine of thisinvention a continuous die, it is also within the scope of the saidinvention to employ two or more adjoining or longitudinally spaced fixeddies or die sections each adapted to perform at least one of theprogressive stages of the tube drawing process.

As will be appreciated, the fixed die parts or portions may be madereadily removable and replaceable by others, according to thecross-sectional shape and dimensions of the tubing to be produced.

The leading section of the die head may conveniently be so contoured asfirst to fold an initially fiat strip of metal into a U formation insection with widely separated 2 limbs, and to reduce the width of the Uuntil the limbs (to constitute the sides of the drawn tubing) are spacedapart only a short distance and parallel to each other, with one of thelimbs extending a little beyond the other. The opposed complementary andappropriately contoured parts of the following portion or section of thedie head may then act to bend the free edge of the shorter limb firstinwards towards and then parallel to the longer limb so as to form alongitudinal flange, next to bend the projecting edge of the longer limbfirst laterally inwards and then downwards so that it enfolds theaforesaid flange to produce a tube-closing seam, and finally to bend theinter-engaged portions of the two limbs constituting the seam so thatthey lie against one of the narrow sides of the resulting flat sectionlock seamed tubing.

The improved and simplified machine of this invention also essentiallyincludes means for gripping and feeding forwards the finished tubingemerging from the die head and so continuously drawing the strip metalthrough the die or dies. The feeding means may be of any suitablecharacter, although it is preferred to employ for this purpose a pair ofappropriately knurled or similarly formed wheels. Alternatively, thefeeding means may comprise an endless roller or equivalent chainfurnished with pairs of laterally spaced shoes arranged at respectivelyopposite sides of the tubing issuing from the die head, and relativelystationary parts adapted, during travel of the chains, to cause thepairs of shoes to grip the tubing seriatim and so draw it continuouslyforwards through the die head.

It is necessary to associate with the die head a mandrel about which thetubing can be formed, this mandrel also serving to prevent the grip ofthe feeding means from crushing the said tubing.

Immediately following the die head there is provided a pair of rollerswhich are arranged to engage and press upon the narrow sides of the lockseamed tubing for the purpose of squeezing down and fiattening thetube-closing seam and bringing the tubing to the correct size.

In order that the invention may be more. clearly understood and readilycarried into practical effect, a specific constructional example of thenew or improved tube drawing machine will now be described withreference to the accompanying drawings, wherein,

Figures 1 and 1A are general perspective views of the principal sectionof the machine showing, inter alia, the die head, the mounting for therollers arranged'to squeeze down and flatten the tube-closing seam, andthe knurled feed wheels, the perspective view having been divided alongthe common dot-dash line of each, a a

Figure 2 is a side view of the rollers for squeezing down and flattening.the tube-closing seam, i T

Figure 3 is a cross-sectional view taken on the line 111111 of Figure 2,

Figure 4 is a more or less diagrammatic representation, in explodedform, showing a length of tubing as it appears at various stages duringclosing of the same, and also the opposed sets of die plates employed toproduce the tube-closing seam,

Figures 5 and 6 depict more clearly the operative ends of the die platesof two opposed sets respectively,

Figures 7 and 8 are detail perspective views of the operative ends oftwo of the said die plates, and

Figures 9-12 are detail sectional views illustrating successive stagesin the closing of the tubing.

Like parts are designated by similar reference characters throughout thedrawings.

Referring to Figure 1A, it will be seen that the die head, indicatedgenerally by the letter A, comprises a leading sheet metal trough 1, afollowing unit 2 consisting of two blocks 3 and 4 which are arrangedside, by

side with a distance piece between them suchwise as to provide alongitudinally extending channel 5, and which have clamped to the topsurfaces thereof opposed sets of fixed die plates 6--12. The trough 1, aportion only of which is depicted in Figure 1A, is so contoured andformed at the top with inwardly directed flanges In as first to fold aninitially flat metal, e.g. copper strip such as that indicated at 13 inFigures 9-12 into a U formation in section with widely separated limbsand then to reduce the width of the U until the limbs 13a and 13bare'spaced apart only a short distance and are parallel to each other,with the limb 13a extending a little beyond the limb 1312. Thisintermediate stage in the conversion of the strip metal from the flatcondition into lock seamed tubing (of the cross-section shown in Figure12) occurs immediately prior to the stage illustrated in Figure 9. Thetrough 1, moreover, is mounted on supporting legs 14 which stand on adrip tray 15 in turn carried by a platform 16 mounted on a bed 17.During the initial folding operation performed by the appropriatelycontoured trough 1, the strip metal may advantageously be lubricatedwith oil, in which instance the surplus oil would be collected in thetray 15.

The unit 2, with its opposed sets of fixed die plates 612, is alsomounted on the platform 16 and functions to close the tubing drawnthrough the channel 5. Thus, as the folded metal strip 13 issues fromthe trough 1 the upper end portions of the upstanding limbs 13a and 13bfirst pass between the operative ends of the pair of opposed die plates6 and 7. As will be seen from Figures 4, 5, 6 and 9, the operative endof the die plate 6 is wholly fiat and disposed in a vertical plane,whereas the opposed end of the die plate 7 is curved and formed at theappropriate top corner thereof with a laterally protruding lip 7a. Theend of the plate 6 accordingly has no appreciable effect on the upwardlyprojecting edge portion 130 of the longer limb 13a, but the action ofthe plate 7 on the free edge 13d of the shorter limb 13b is to bend thisfirst inwardly and then parallel to the said longer limb so as toproduce a longitudinal flange Be. The upper edge portions of the limbs13a and 13b then pass between the opposed die plates 8 and 9. As shownmore clearly in Figures and 7, the upper portion of the operative end ofthe plate 8 is formed with a suitably curved lateral projection 8a,whilst the top surface of the operative end portion of the opposed plate9 is so rabbetted as depicted in Figures 4 and 10, as to provide thereona flange 9a having a curved leading end and the underside of which isflush with the bottom of the last mentioned plate. The action of thelateral projection 8a on the projecting edge 130 of the longer limb 13ais to bend this edge down fiat onto the flange 9a so that it extendslaterally inwards and assumes a horizontal disposition as illustrated inFigure 10. Next, the edges of the limbs 13a and 13b pass between theopposed die plates 10 and 11. The operative end of the plate 10, likethat of the plate 6, is fiat and vertically disposed (Figures 4 and 5),but the opposed end portion of the plate 11 is so contoured andrabbetted on its underside, as shown more clearly in Figure 6, as toprovide thereon an overhanging lip 11a adapted to act on the projectingedge 130 of the longer limb 13a and bend this edge vertically downwardsso that it embraces the aforementioned longitudinal flange 13a andproduces a tube-closing seam 13f (see Figure 11). Finally, theinterengaged portions of the limbs 13a and 13b constituting the sideseam, as they travel forwardly beneath a curved and laterally extendingformation 12a (see Figure 8) on the operative end of the last die plate12, are bent over at right angles so as to lie against the adjacentnarrow side of the flat section lock seamed tubing T thus produced (seeFigure 12). It will be noted that the die plate 12 is a single one andnot one of a pair.

As will be appreciated from Figures 1A and 4, each of the die plates6-12 has formed therein a hole 18 to enable it to be engaged over theappropriate one of a series of screwed locating studs 19 extendingvertically upwards from the top surface of the relevant one of the twoopposed die blocks 3 and 4. The said plates are clamped in position onthe tops of the blocks by means of nuts 20 screwed onto the upwardlyprojecting portions of the studs 19.

Arranged to extend right through the channel 5 in the die unit 2 is afiat section bar 21 constituting a mandrel about which the tubing T isformed. The tail end of the mandrel 21 is connected by means of suitablelinkage with a lever 22 whereby the mandrel can be withdrawn from andprojected into the unit 2 as occasion may demand. The lever 22 issecured upon a spindle 23 arranged to turn in plates 24 attached to theoutsides of the blocks 3 and 4. A screw having a knurled head 25 isprovided for locking the mandrel in its operative position. Preparatoryto starting up the machine, the leading end of the strip metal can bepushed through the die unit 2 with the aid of the mandrel 21.

For gripping and feeding forwards the finished tubing T emerging fromthe die unit 2, and thereby continuously drawing the strip metal throughthe die head A, there is provided in this particular example a pair offeed wheels 26 and 27 (Figures 1 and 1A). These wheels, which arehorizontally disposed and arranged to revolve about vertical axes, arelocated between a base plate 28 andthe superimposed horizontal member 29of a bridge structure 30. It is convenient here to mention that themandrel 21 is sufficiently long to extend between the feed wheels 26 and27 for the purpose of preventing the grip exerted by the latter fromcrushing the tubing. The bearings for the spindle of the feed wheel 26are fixed and this wheel is adapted to be continuously driven, e.g. froman electric motor through the medium of reduction gearing. The feedwheel 27, on the other hand, is driven from the companion wheel 26 forwhich purpose the wheels are integrally combined with intermeshing spurgears 31 and 32. Moreover, to enable the feed wheels to grip the tubingT yieldingly between them the spindle of the feed wheel 27 is mounted torotate in spring-influenced bearing blocks 33 (Figure l) which areslidable in transverse slots 34 and 35 formed in the base plate 28 andthe superimposed member 29 respectively. Compression springs 36 areaccommodated within the slots 34 and 35 for action upon the slidablebearing blocks 33, and manually operable screws 37 are provided foradjusting the spring pressure, according to requirements. The referencenumeral 38 indicates oiling nipples. The feed wheels 26 and 27 areperipherally recessed at 39 to receive and engage the respectivelyopposite sides of the lock seamed tubing T, and the bottoms or backs ofthe recesses are knurled at 40 to enhance the grip of the wheels on thetubing. As it issues from the nip of the feed wheels 26 and 27 thetubing passes between pairs of conventional straightening rolls such as41 and 42 the inner faces of which are circumferentially rabbetted inknown manner for engagement with the outerside of the tubing. There aretwo spaced pairs of the rolls 41 and an intermediate single pair ofrolls 42 mounted on manually adjustable eccentrics. In Figure 1 only oneof the pairs of rolls 41 is shown, the other pair being hidden by thefeed wheel 27 and the bridge structure 30.

Located between the die unit 2 and the feed wheels 26 and 27, asillustrated in Figures 2 and 3, is a pair of superimposed rollers 43 and44 adapted, by engagement with the narrow sides of the tubing T, tosqueeze the latter to correct size widthwise by flattening thetubeclosing seam 13]. Of these two rollers the bottom or bed roller 43is disposed in a vertical space between the rear ends of the two dieblocks 3 and 4 and is provided with an axle 45 the opposite ends ofwhich are located in co-axial holes 46 formed in the said blocks asshown in Figure 3. The top roller 44, on the other hand, is

arranged to' revolve within a vertical recess 47 formed in a block 48disposed above and transversely across the rear ends of the die blocks 3and 4. The block 48 is drilled right through to provide a hole 49 forreception of the axle 50 of the roller 44. Ball bearings mayadvantageously be provided between the axles 45 and 50 and the rollers43 and 44 respectively. The block 48 is also vertically drilled forengagement with and to enable it to slide up and down along two parallelspaced vertical slide rods 51 the lower ends of which are set in the dieblocks 3 and 4. The bottom ends of the vertical holes drilled in theblock 48 are counterbored to receive compression springs 52 whichsurround the slide rods 51 and are interposed between the blocks 3 and 4and the superimposed block 48. The tops of the rear ends of the blocks 3and 4 are slightly recessed to enable the top roller 44 to engage andpress down on the longitudinal seam 13 For depressing the block 48against the action of the compression springs 52 and so causing theroller 44 to engage the tubing, under the required degree of pressure,there is provided a vertically disposed adjustable screw 53 the leading,i.e. lower, end of which is turned down into the form of a plunger 54adapted to fit within and to act on the bottom of a hole 55 formed inthe top of the said block. The screw 53 is engaged in a tapped holeformed in a fixed cross member 56 carried by and at the upper ends ofthe slide rods 5-1. In this connection the upper end portions of thesaid slide rods are reduced in diameter and screwthreaded at 51a toreceive nuts 57 whereby the cross member 56 is secured in position. Locknuts 58 and 59 are provided for locking the screw 53 after an adjustmentthereof.

The machine may also, if desired, include a parting-off saw operable forautomatically sawing off the finished tubing tubes of any desired lengthWhile the machine is in operation.

The strip metal may be be continuously drawn from a coil of the materialin which instance the machine may incorporate a coil holder and anassociated tensioner.

The machine of this invention may, moreover, embody flux, solder orother tanks by which the strip metal can be tinned or soldered eitherbefore or after the tube drawing operation.

The machine may include a sheet metal cabinet upon the top of which aremounted the die head and the feed wheels; within the cabinet would beaccommodated the coil holder and tensioner, the driving means for thefeed wheels, and the flux, solder or other tanks.

I claim:

1. A tube drawing machine for continuously producingquadrangularly-sectioned lock-seamed tubing from an initially fiat stripcomprising, in combination, a U-shaped trough for initially folding themetal strip into a U-formation with one leg of the U slightly longerthan the other leg, a guide channel through which the U-formation can bedrawn, said channel being of such depth that a portion of both legsextends above said channel, a series of die heads overlying saidchannel, the die heads comprising means for bending the free edge of theshorter leg both inwards and upwards parallel to the longer leg to forman L-shaped flange, means for bending the free edge of the longer leglaterally inwards and then downwards to overlap the upper and projectingedge of said first named leg, and further means bending the innerengaged portions of both legs over the lie adjacent to the horizontalportion of said shorter leg, a pair of superimposed sizing rollershaving horizontal axes and adapted to press upon the upper and lowersides of the tubing to compress the closing seam and thus accuratelysize the tubing, a pair of knurled feed wheels rotatable about verticalaxes between the nip of which the tubing passes, means for driving thewheels, said wheels gripping the vertical sides of the tubing andfeeding forwards the finished tubing emerging from the sizing rollersthereby continuously drawing the metal strip through the latter, and amandrel of uniform cross-section extending through the channel andbetween the feed wheels about which the tubing is formed, said mandrelbeing rigidly held by linkage means attached at the entrance to saidchannel.

2. A tube drawing machine according to claim 1, wherein said die meansinclude a first pair of die plates the operative end of one is whollyflat and disposed in a vertical .plane whereas the opposed end of theother is curved and formed at one of the top corners thereof with alaterally protruding lip, the end of the first mentioned plate having noappreciable effect on an upwardly projecting edge portion of a longerlimb of an initially folded strip, but the opposed end of the secondmentioned plate being adapted, by action on the free edge of the shorterlimb of the folded strip, to bend this edge first inwards and thenparallel to the said longer limb.

3. A tube drawing machine according to claim 2, wherein the upperportion of the operative end of one of the second pair of die plates isformed with a curved lateral projection whilst the top surface of theoperative end portion of the opposed die plate is so rabbetted as toprovide thereon a flange having a curved leading end the underside ofwhich is flush with the bottom of the last mentioned plate, the actionof the aforesaid lateral projection on the projecting edge of the longerlimb of the folded strip being to bend this edge down onto the flange sothat the said edge extends laterally inwards.

4. A tube drawing machine according to claim 3, wherein the operativeend of one of the third pair of die plates is flat and verticallydisposed, whereas the opposed end portion of the other plate of the pairis so contoured and rabbetted on its underside as to provide thereon anoverhanging lip adapted to act on the projecting edge of the longer limbof the folded strip and bend this edge vertically downwards so that itembraces a previously formed flange on the shorter limb to produce atube-closing seam.

5. A tube drawing machine according to claim 4, wherein a single dieplate following the third pair of opposed die plates has a curved andlaterally extending formation on its operative end, this formation beingadapted, by action on the interengaged portions of the limbsconstituting the tube-closing seam, to bend these portions over so thatthey lie against the adjacent narrow side of the lock seamed tubing.

References Cited in the file of this patent UNITED STATES PATENTS617,363 Skogse Jan. 10, 1899 734,300 Cairns July 21, 1903 1,034,954Beebe Aug. 6, 1912 1,137,966 Groehn May 4, 1915 1,224,046 Turley Apr.24, 1917 1,327,641 Stolp Ian. 13, 1920 1,461,848 Jaquiery July 17, 19231,468,635 Higgins Sept. 25, 1923 1,652,396 Dallas Dec. 13, 19271,865,069 Allen June 28, 1932 2,141,200 Sundback Dec. 27, 1938 2,333,997Glans Nov. 9, 1943 2,648,842 Shockey ct a1. Aug. 18, 1953

